From d08be913924050f4274c68edd44f29aaa0d17dae Mon Sep 17 00:00:00 2001
From: logaritmisk <anders.e.olsson@gmail.com>
Date: Tue, 20 Dec 2016 08:05:02 +0100
Subject: [PATCH] 2016/16

---
 2016/16/Cargo.lock  |  4 +++
 2016/16/Cargo.toml  |  6 ++++
 2016/16/src/main.rs | 82 +++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 92 insertions(+)
 create mode 100644 2016/16/Cargo.lock
 create mode 100644 2016/16/Cargo.toml
 create mode 100644 2016/16/src/main.rs

diff --git a/2016/16/Cargo.lock b/2016/16/Cargo.lock
new file mode 100644
index 0000000..44ecfe1
--- /dev/null
+++ b/2016/16/Cargo.lock
@@ -0,0 +1,4 @@
+[root]
+name = "16"
+version = "0.1.0"
+
diff --git a/2016/16/Cargo.toml b/2016/16/Cargo.toml
new file mode 100644
index 0000000..a6c949e
--- /dev/null
+++ b/2016/16/Cargo.toml
@@ -0,0 +1,6 @@
+[package]
+name = "16"
+version = "0.1.0"
+authors = ["logaritmisk <anders.e.olsson@gmail.com>"]
+
+[dependencies]
diff --git a/2016/16/src/main.rs b/2016/16/src/main.rs
new file mode 100644
index 0000000..c840342
--- /dev/null
+++ b/2016/16/src/main.rs
@@ -0,0 +1,82 @@
+pub fn generate_data(input: &str) -> String {
+    let mut data = input.to_owned();
+
+    data.push('0');
+
+    for c in input.chars().rev() {
+        data.push(if c == '0' { '1' } else { '0' });
+    }
+
+    data
+}
+
+pub fn calculate_checksum(input: &str) -> String {
+    let mut data = String::new();
+
+    for pair in input.as_bytes().chunks(2) {
+        data.push(if pair[0] == pair[1] { '1' } else { '0' })
+    }
+
+    data
+}
+
+pub fn fill_disk(state: &str, length: usize) -> (String, String) {
+    let mut state = state.to_owned();
+
+    while state.len() < length {
+        state = generate_data(&state);
+    }
+
+    state.truncate(length);
+
+    let mut checksum = calculate_checksum(&state);
+
+    while checksum.len() % 2 == 0 {
+        checksum = calculate_checksum(&checksum);
+    }
+
+    (state, checksum)
+}
+
+
+fn main() {
+    let data = fill_disk("01110110101001000", 272);
+
+    println!("checksum_1={}", data.1);
+
+    let data = fill_disk("01110110101001000", 35651584);
+
+    println!("checksum_2={}", data.1);
+}
+
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn example_01() {
+        assert_eq!("100".to_owned(), generate_data("1"));
+    }
+
+    #[test]
+    fn example_02() {
+        assert_eq!("001".to_owned(), generate_data("0"));
+    }
+
+    #[test]
+    fn example_03() {
+        assert_eq!("11111000000".to_owned(), generate_data("11111"));
+    }
+
+    #[test]
+    fn example_04() {
+        assert_eq!("1111000010100101011110000".to_owned(), generate_data("111100001010"));
+    }
+
+    #[test]
+    fn example_05() {
+        assert_eq!("110101".to_owned(), calculate_checksum("110010110100"));
+        assert_eq!("100".to_owned(), calculate_checksum("110101"));
+    }
+}